The recent celebration of the discoveries made by Galileo four centuries ago has attracted new attention to the refracting telescope and to its use as an instrument for the observation of the night sky. This has offered the opportunity for addressing in the classroom the basic principles explaining the operation of the telescope. When doing so, a…

Discusses various types of transducers and explains the use of a photoresistor in sensing light. Describes various hardware and software combinations which can be used with photoresistors in science laboratory experiments. Presents general applications of this instrument in light-meter, solarimeter, and colorimeter experiments. (TW)